Thorlabs BS008 Beamsplitter Cube

The Thorlabs BS008 is a precision optical beamsplitter cube designed to split an incident light beam into two paths of nearly equal intensity with minimal polarization dependence. It operates over the 700–1100 nm wavelength range, making it suitable for visible to near-infrared applications commonly used in research, imaging, interferometry, and laser systems.

• Function: 50:50 (R:T) non-polarizing beam splitting

• Wavelength Range: 700 nm to 1100 nm

• Cube Size: 5 mm side length

• Material: N-BK7 optical glass

• Coatings:

  • Broadband antireflective (AR) coatings on all external faces to reduce reflection losses

  • Beamsplitting coating on the internal diagonal surface for balanced split ratios

• Performance:

  • Very low transmitted wavefront distortion (< λ/4 at 633 nm)

  • Low polarization dependence: |Tₛ − Tₚ| and |Rₛ − Rₚ| each < 10%

  • Typical split efficiency: ~47 % transmitted and reflected, with > 90 % total throughput

These features make the BS008 ideal for laboratory setups where consistent, balanced splitting of collimated laser or broadband light is required without introducing significant polarization artifacts.

🛠 Typical Uses

• Interferometry and metrology

• Laser beam sampling

• Optical test benches

• Microscopy and imaging systems

Versatile and compact, the 5 mm cube fits standard optical mounts and cage systems.